A Comprehensive Introduction of Core Crawler Crane Components
What is a Crawler Crane?
A crawler crane is a large lifting device mounted on a crawler undercarriage. It includes a traveling mechanism, a lifting mechanism, a luffing mechanism, and slewing mechanism. Unlike ordinary truck cranes, it uses two wide tracks as its “feet,” enabling it to move and operate stably on various complex and rugged terrains, such as soft mud, sand, and even slopes. Therefore, it is widely used in heavy lifting applications such as construction sites, bridge construction, power plant construction, and equipment installation.
Detailed Crawler Crane Components Analysis
1. Hook Assembly
Includes: The crane hook assembly includes the hook itself, the hook nut, the thrust bearing, the pulley system, and the housing.
Function: The hook assembly is the lifting device of the crawler crane and a universal connection hub. It works in conjunction with rigging such as wire rope clips (lifting straps, shackles) to lift heavy objects. The thrust bearing allows the hook to rotate freely under load, preventing the wire rope from twisting.
2. Boom System
Crane Type
The main crane boom structures are primarily of two types: truss booms and telescopic booms.
Truss Boom:
A lattice structure constructed from steel sections (angle steel, channel steel) connected by pins.
Advantages: Lightweight, small windward area, large lifting height, and capacity.
Disadvantages: Time-consuming and labor-intensive assembly, disassembly, and length changes; low automation.
Applications: Large crawler cranes, large tower cranes.
Box-Type Telescopic Boom:
A high-strength box-shaped structure welded from steel plates. The boom sections extend and retract via hydraulic cylinders or wire rope systems.
Advantages: Good mobility, rapid extension and retraction, high operating efficiency.
Disadvantages: Heavyweight; extremely high requirements for materials and manufacturing processes.
Applications: Truck cranes, tire cranes, all-terrain cranes.
Function:
The boom is the core steel structural component supporting the lifting wire rope and pulley block. It connects to the upper slewing platform via a hinged mechanism, and its length can be extended by adding intermediate sections. Furthermore, an auxiliary boom can be installed at the top of the main boom to further expand the crane’s working range.
3. Upper Slewing Upperworks
The upper slewing assembly is located above the middle of the crane and contains all operating and control systems installed on the slewing platform, excluding the boom and hook. The upper slewing assembly is connected to the undercarriage via a slewing bearing mechanism, enabling 360° full rotation operation.
Composition: The upper slewing assembly includes a power system, hydraulic system, control system, and main transmission mechanism.
Power System
Diesel Engine: The diesel engine is located at the rear or middle of the platform and provides mechanical power to the crawler crane.
Main Hydraulic Pump: The main hydraulic pump is connected to the engine and converts the engine’s mechanical energy into hydraulic energy.
Control System
Operator’s Station: The operator’s cab is located at the front of the platform and is the crane’s “cab.”
Control levers and pedals: Control the lifting, luffing, and slewing of the crawler crane.
Electronic control system
Receives operating commands and converts them into electrical signals to control the hydraulic valves.
Torque limiter display: The torque limiter display is the crane’s safety information display center, showing real-time data such as lifting weight, luffing radius, rated load, and boom angle.
Various instruments and switches: Monitor the status of the engine and hydraulic system.
Main hoisting system
Hoisting mechanism: The hoisting mechanism typically consists of two hoists, a main hoist and an auxiliary hoist, mainly composed of a hydraulic motor, a gearbox, a brake, and a drum.
Hoist gearbox: Converts the high-speed, low-torque output of the hydraulic motor into the low-speed, high-torque output required by the drum.
Fail-safe brake: Automatically brakes the drum when the hydraulic pressure is released, preventing the load from falling.
Slewing System
Slewing mechanism: The device that drives the upper assembly to rotate, including a slewing hydraulic motor, a slewing gearbox, a slewing pinion, and a slewing brake.
Hydraulic Control System
Main Control Valve Assembly: Controls the flow direction, flow rate, and pressure of hydraulic oil based on electrical signals from the control room, thereby directing the actions of the hoist, luffing, and slewing mechanisms.
Pilot Control System
Drives the main control valves.Hydraulic Oil Tank and Related Piping: Stores, cools, and transports hydraulic oil.
Electrical System
The electrical system includes subsystems such as the main circuit, control circuit, monitoring circuit, braking control circuit, torque limiter circuit, and automatic stop circuit. Modern crawler crane electrical systems not only have basic power distribution and control functions but also integrate advanced functions such as intelligent monitoring, fault diagnosis, and data logging.
Safety System
Crawler cranes are equipped with multiple safety protection devices:
Lifting height limiter: Prevents excessive winding of the wire rope.
Radius Limiter: Limits the working angle range of the boom.
Torque limiter: The core protection device calculates the working torque in real time and intervenes accordingly.
Boom angle indicator: Displays the real-time working angle of the boom.
Safety locks: Includes mechanical protection mechanisms such as winch pawls and luffing pawls.
Multi-mode braking system: Includes winch brake, slewing brake, and travel brake.
Slewing locking device: Mechanically locks the upper slewing platform during maintenance.
4. Counterweight System
Counterweight block: Located at the rear of the slewing platform, composed of heavy-duty cast iron blocks. It balances the enormous overturning forces generated by the boom and load during operation, preventing the crawler crane from tipping over. For easy transport, the counterweight is usually removable.
5. Undercarriage System
The walking system mainly includes the track assembly, drive wheels, guide wheels, track rollers, upper support rollers, travel motor, travel gearbox, track tensioning device, and track telescopic cylinders. It enables the crawler crane to operate smoothly on the ground.
Crawler Crane Undercarriage Components
- Travel Motor: Receives high-pressure oil from the hydraulic system and outputs rotational power.
- Travel Gearbox: Combined with the travel motor, it is a key component for power amplification and deceleration.
- Track Shoe Assembly: The track shoes directly contact the ground, distributing lifting pressure and preventing the crane from sinking into soft or muddy ground. It provides the necessary traction for the crane to move and climb slopes. Simultaneously, it protects internal core components such as the track rollers, guide wheels, and drive chain, extending the service life of the entire chassis. Therefore, the track shoes are crucial components determining the stability and durability of the crawler crane.
- Sprocket: Mounted on the gearbox, they are the core transmission component of the crawler crane, transmitting the rotational power of the travel motor to drive the entire track chain.
- Idler: Crane Idlers are typically integrated with the tensioning device and located at the front of the track frame, guiding the direction of track movement.
- Bottom Roller: Bottom rollers are a row of wheels mounted below the track frame, bearing the weight of the crane and rolling along the track.
- Top Roller: Upper rollers are mounted above the track frame, supporting the upper part of the crane track shoe, guiding and restraining it, and preventing excessive sagging and swaying due to their own weight.
- Track Tensioning Device: Typically consists of a tensioning cylinder and an energy accumulator, possessing a certain degree of elasticity to cushion impacts during crawler crane movement.
- Frame: Contains the traveling frame and track beams, forming the structural foundation of the entire crawler crane chassis system.
- Travel Brakes: Located inside the travel motor or gearbox, enabling parking braking and emergency braking.
Crawler Crane Undercarriage Suppliers
As the core load-bearing crawler crane component, the crane undercarriage parts directly bear all the pressure during crawler crane lifting operations and movement. Choosing high-quality crawler crane undercarriage parts effectively distributes stress, prevents track plate deformation and fatigue damage, thereby reducing the risk of crawler crane overturning.
VM® crawler crane undercarriage components have undergone extensive testing and demonstrate superior stability and durability in complex construction environments, significantly extending equipment lifespan and reducing downtime and high maintenance costs caused by component failure. Choose VM® to safeguard your crawler crane operations!
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